#define  _CRT_SECURE_NO_WARNINGS

class Solution
{
 public:
	 int missingNumber(vector<int>& nums)
	 {
		 int left = 0, right = nums.size() - 1;
		 while (left < right)
		 {
			 int mid = left + (right - left) / 2;
			 if (nums[mid] == mid) left = mid + 1;
			 else right = mid;
		 }
		 return left == nums[left] ? left + 1 : left;
	 }
};